My Blender is crashing after I installed an addon twice by accident. How can I fix it?
When you say that you deleted the /scripts folder, what do you mean exactly? You should never delete the folder that is under the blender installation path, as that will mean Blender cannot start up (some scripts are essential).

When you add an add-on from File -&gt; User Preferences, it will be copied to your local blender user  directory. This is ~/.config/blender/[VERSION].

No matter where it is installed, Blender will be looking in ~/.config/blender/[VERSION] for add-ons, which might explain why they are still present even after you have purged the installation directory and reinstalled.

If you haven't already, try deleting ~/.config/blender/[VERSION] (if my memory serves, it would be sudo rm -r ~/.config/blender/[VERSION]). Then reinstall a fresh copy of Blender via your preferred mechanism (e.g. Steam).

[VERSION] should be 2.78 or whatever you are using.